【READ BEFORE ANSWERING: Reference Concepts】

Please read the following principles to assist your reasoning:

1. Cache Coherence: The MESI protocol is a foundational hardware-based cache coherence mechanism designed to maintain data consistency across the private caches of a multi-core system. It functions by assigning one of four distinct states to every cache line—Modified (M), Exclusive (E), Shared (S), or Invalid (I)—and monitoring bus traffic through a process known as "snooping." Under this protocol, if a core intends to write to a data block currently in the Shared state, it must first broadcast an Invalidate signal to all other cores to force their local copies into the Invalid state; this allows the initiating core to acquire exclusive ownership and transition to the Modified state, ensuring that no two cores can hold conflicting versions of the same data and that all processors always access the most recent values.
2. Pipeline Overhead: Pipelining increases Throughput. However, due to 'Pipeline Registers' inserted between stages, the setup/propagation time causes the total Latency of a 'single instruction' to increase slightly compared to a non-pipelined design.
3. Memory Hierarchy Goals: L1 Cache optimizes for Speed (Hit Time). L2 Cache optimizes for reducing the Global Miss Rate (intercepting Misses before they reach the slow DRAM). L2 is typically slower and larger than L1.
4. Branch Limits: In fixed-length ISAs (e.g., RISC-V), the Offset for conditional branches is limited (e.g., 12-bit, approx KB). Long-distance jumps (e.g., 1MB) require compiler workarounds (like trampolines).
5. Spatial Locality: Cache moves data in Blocks. If a program's access Stride is too large (e.g., jumping across rows in a large 2D array), it fails to utilize the data within the block, leading to a high Miss Rate.

INSTRUCTIONS:

1. Use the Reference Concepts above to assist your reasoning.
2. WARNING: Column B contains 'Distractors' (Incorrect Statements).
3. Column B has MORE options than Column A. Select the BEST match for each item in Column A.

問題2: Scenario Analysis (25 points)